path: root/src/backend/catalog/pg_publication.c

/*-------------------------------------------------------------------------
 *
 * pg_publication.c
 *		publication C API manipulation
 *
 * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *		src/backend/catalog/pg_publication.c
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include "access/genam.h"
#include "access/heapam.h"
#include "access/htup_details.h"
#include "access/tableam.h"
#include "access/xact.h"
#include "catalog/catalog.h"
#include "catalog/dependency.h"
#include "catalog/index.h"
#include "catalog/indexing.h"
#include "catalog/namespace.h"
#include "catalog/partition.h"
#include "catalog/objectaccess.h"
#include "catalog/objectaddress.h"
#include "catalog/pg_inherits.h"
#include "catalog/pg_namespace.h"
#include "catalog/pg_publication.h"
#include "catalog/pg_publication_namespace.h"
#include "catalog/pg_publication_rel.h"
#include "catalog/pg_type.h"
#include "commands/publicationcmds.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/catcache.h"
#include "utils/fmgroids.h"
#include "utils/inval.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/syscache.h"

static void publication_translate_columns(Relation targetrel, List *columns,
										  int *natts, AttrNumber **attrs);

/*
 * Check if relation can be in given publication and throws appropriate
 * error if not.
 */
static void
check_publication_add_relation(Relation targetrel)
{
	/* Must be a regular or partitioned table */
	if (RelationGetForm(targetrel)->relkind != RELKIND_RELATION &&
		RelationGetForm(targetrel)->relkind != RELKIND_PARTITIONED_TABLE)
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
				 errmsg("cannot add relation \"%s\" to publication",
						RelationGetRelationName(targetrel)),
				 errdetail_relkind_not_supported(RelationGetForm(targetrel)->relkind)));

	/* Can't be system table */
	if (IsCatalogRelation(targetrel))
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
				 errmsg("cannot add relation \"%s\" to publication",
						RelationGetRelationName(targetrel)),
				 errdetail("This operation is not supported for system tables.")));

	/* UNLOGGED and TEMP relations cannot be part of publication. */
	if (targetrel->rd_rel->relpersistence == RELPERSISTENCE_TEMP)
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
				 errmsg("cannot add relation \"%s\" to publication",
						RelationGetRelationName(targetrel)),
				 errdetail("This operation is not supported for temporary tables.")));
	else if (targetrel->rd_rel->relpersistence == RELPERSISTENCE_UNLOGGED)
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
				 errmsg("cannot add relation \"%s\" to publication",
						RelationGetRelationName(targetrel)),
				 errdetail("This operation is not supported for unlogged tables.")));
}

/*
 * Check if schema can be in given publication and throw appropriate error if
 * not.
 */
static void
check_publication_add_schema(Oid schemaid)
{
	/* Can't be system namespace */
	if (IsCatalogNamespace(schemaid) || IsToastNamespace(schemaid))
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
				 errmsg("cannot add schema \"%s\" to publication",
						get_namespace_name(schemaid)),
				 errdetail("This operation is not supported for system schemas.")));

	/* Can't be temporary namespace */
	if (isAnyTempNamespace(schemaid))
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
				 errmsg("cannot add schema \"%s\" to publication",
						get_namespace_name(schemaid)),
				 errdetail("Temporary schemas cannot be replicated.")));
}

/*
 * Returns if relation represented by oid and Form_pg_class entry
 * is publishable.
 *
 * Does same checks as the above, but does not need relation to be opened
 * and also does not throw errors.
 *
 * XXX  This also excludes all tables with relid < FirstNormalObjectId,
 * ie all tables created during initdb.  This mainly affects the preinstalled
 * information_schema.  IsCatalogRelationOid() only excludes tables with
 * relid < FirstUnpinnedObjectId, making that test rather redundant,
 * but really we should get rid of the FirstNormalObjectId test not
 * IsCatalogRelationOid.  We can't do so today because we don't want
 * information_schema tables to be considered publishable; but this test
 * is really inadequate for that, since the information_schema could be
 * dropped and reloaded and then it'll be considered publishable.  The best
 * long-term solution may be to add a "relispublishable" bool to pg_class,
 * and depend on that instead of OID checks.
 */
static bool
is_publishable_class(Oid relid, Form_pg_class reltuple)
{
	return (reltuple->relkind == RELKIND_RELATION ||
			reltuple->relkind == RELKIND_PARTITIONED_TABLE) &&
		!IsCatalogRelationOid(relid) &&
		reltuple->relpersistence == RELPERSISTENCE_PERMANENT &&
		relid >= FirstNormalObjectId;
}

/*
 * Filter out the partitions whose parent tables were also specified in
 * the publication.
 */
static List *
filter_partitions(List *relids)
{
	List	   *result = NIL;
	ListCell   *lc;
	ListCell   *lc2;

	foreach(lc, relids)
	{
		bool		skip = false;
		List	   *ancestors = NIL;
		Oid			relid = lfirst_oid(lc);

		if (get_rel_relispartition(relid))
			ancestors = get_partition_ancestors(relid);

		foreach(lc2, ancestors)
		{
			Oid			ancestor = lfirst_oid(lc2);

			/* Check if the parent table exists in the published table list. */
			if (list_member_oid(relids, ancestor))
			{
				skip = true;
				break;
			}
		}

		if (!skip)
			result = lappend_oid(result, relid);
	}

	return result;
}

/*
 * Another variant of this, taking a Relation.
 */
bool
is_publishable_relation(Relation rel)
{
	return is_publishable_class(RelationGetRelid(rel), rel->rd_rel);
}

/*
 * Returns true if any schema is associated with the publication, false if no
 * schema is associated with the publication.
 */
bool
is_schema_publication(Oid pubid)
{
	Relation	pubschsrel;
	ScanKeyData scankey;
	SysScanDesc scan;
	HeapTuple	tup;
	bool		result = false;

	pubschsrel = table_open(PublicationNamespaceRelationId, AccessShareLock);
	ScanKeyInit(&scankey,
				Anum_pg_publication_namespace_pnpubid,
				BTEqualStrategyNumber, F_OIDEQ,
				ObjectIdGetDatum(pubid));

	scan = systable_beginscan(pubschsrel,
							  PublicationNamespacePnnspidPnpubidIndexId,
							  true, NULL, 1, &scankey);
	tup = systable_getnext(scan);
	result = HeapTupleIsValid(tup);

	systable_endscan(scan);
	table_close(pubschsrel, AccessShareLock);

	return result;
}

/*
 * SQL-callable variant of the above
 *
 * This returns null when the relation does not exist.  This is intended to be
 * used for example in psql to avoid gratuitous errors when there are
 * concurrent catalog changes.
 */
Datum
pg_relation_is_publishable(PG_FUNCTION_ARGS)
{
	Oid			relid = PG_GETARG_OID(0);
	HeapTuple	tuple;
	bool		result;

	tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
	if (!HeapTupleIsValid(tuple))
		PG_RETURN_NULL();
	result = is_publishable_class(relid, (Form_pg_class) GETSTRUCT(tuple));
	ReleaseSysCache(tuple);
	PG_RETURN_BOOL(result);
}

/*
 * Gets the relations based on the publication partition option for a specified
 * relation.
 */
List *
GetPubPartitionOptionRelations(List *result, PublicationPartOpt pub_partopt,
							   Oid relid)
{
	if (get_rel_relkind(relid) == RELKIND_PARTITIONED_TABLE &&
		pub_partopt != PUBLICATION_PART_ROOT)
	{
		List	   *all_parts = find_all_inheritors(relid, NoLock,
													NULL);

		if (pub_partopt == PUBLICATION_PART_ALL)
			result = list_concat(result, all_parts);
		else if (pub_partopt == PUBLICATION_PART_LEAF)
		{
			ListCell   *lc;

			foreach(lc, all_parts)
			{
				Oid			partOid = lfirst_oid(lc);

				if (get_rel_relkind(partOid) != RELKIND_PARTITIONED_TABLE)
					result = lappend_oid(result, partOid);
			}
		}
		else
			Assert(false);
	}
	else
		result = lappend_oid(result, relid);

	return result;
}

/*
 * Returns the relid of the topmost ancestor that is published via this
 * publication if any and set its ancestor level to ancestor_level,
 * otherwise returns InvalidOid.
 *
 * The ancestor_level value allows us to compare the results for multiple
 * publications, and decide which value is higher up.
 *
 * Note that the list of ancestors should be ordered such that the topmost
 * ancestor is at the end of the list.
 */
Oid
GetTopMostAncestorInPublication(Oid puboid, List *ancestors, int *ancestor_level)
{
	ListCell   *lc;
	Oid			topmost_relid = InvalidOid;
	int			level = 0;

	/*
	 * Find the "topmost" ancestor that is in this publication.
	 */
	foreach(lc, ancestors)
	{
		Oid			ancestor = lfirst_oid(lc);
		List	   *apubids = GetRelationPublications(ancestor);
		List	   *aschemaPubids = NIL;

		level++;

		if (list_member_oid(apubids, puboid))
		{
			topmost_relid = ancestor;

			if (ancestor_level)
				*ancestor_level = level;
		}
		else
		{
			aschemaPubids = GetSchemaPublications(get_rel_namespace(ancestor));
			if (list_member_oid(aschemaPubids, puboid))
			{
				topmost_relid = ancestor;

				if (ancestor_level)
					*ancestor_level = level;
			}
		}

		list_free(apubids);
		list_free(aschemaPubids);
	}

	return topmost_relid;
}

/*
 * Insert new publication / relation mapping.
 */
ObjectAddress
publication_add_relation(Oid pubid, PublicationRelInfo *pri,
						 bool if_not_exists)
{
	Relation	rel;
	HeapTuple	tup;
	Datum		values[Natts_pg_publication_rel];
	bool		nulls[Natts_pg_publication_rel];
	Relation	targetrel = pri->relation;
	Oid			relid = RelationGetRelid(targetrel);
	Oid			pubreloid;
	Publication *pub = GetPublication(pubid);
	AttrNumber *attarray = NULL;
	int			natts = 0;
	ObjectAddress myself,
				referenced;
	List	   *relids = NIL;

	rel = table_open(PublicationRelRelationId, RowExclusiveLock);

	/*
	 * Check for duplicates. Note that this does not really prevent
	 * duplicates, it's here just to provide nicer error message in common
	 * case. The real protection is the unique key on the catalog.
	 */
	if (SearchSysCacheExists2(PUBLICATIONRELMAP, ObjectIdGetDatum(relid),
							  ObjectIdGetDatum(pubid)))
	{
		table_close(rel, RowExclusiveLock);

		if (if_not_exists)
			return InvalidObjectAddress;

		ereport(ERROR,
				(errcode(ERRCODE_DUPLICATE_OBJECT),
				 errmsg("relation \"%s\" is already member of publication \"%s\"",
						RelationGetRelationName(targetrel), pub->name)));
	}

	check_publication_add_relation(targetrel);

	/*
	 * Translate column names to attnums and make sure the column list
	 * contains only allowed elements (no system or generated columns etc.).
	 * Also build an array of attnums, for storing in the catalog.
	 */
	publication_translate_columns(pri->relation, pri->columns,
								  &natts, &attarray);

	/* Form a tuple. */
	memset(values, 0, sizeof(values));
	memset(nulls, false, sizeof(nulls));

	pubreloid = GetNewOidWithIndex(rel, PublicationRelObjectIndexId,
								   Anum_pg_publication_rel_oid);
	values[Anum_pg_publication_rel_oid - 1] = ObjectIdGetDatum(pubreloid);
	values[Anum_pg_publication_rel_prpubid - 1] =
		ObjectIdGetDatum(pubid);
	values[Anum_pg_publication_rel_prrelid - 1] =
		ObjectIdGetDatum(relid);

	/* Add qualifications, if available */
	if (pri->whereClause != NULL)
		values[Anum_pg_publication_rel_prqual - 1] = CStringGetTextDatum(nodeToString(pri->whereClause));
	else
		nulls[Anum_pg_publication_rel_prqual - 1] = true;

	/* Add column list, if available */
	if (pri->columns)
		values[Anum_pg_publication_rel_prattrs - 1] = PointerGetDatum(buildint2vector(attarray, natts));
	else
		nulls[Anum_pg_publication_rel_prattrs - 1] = true;

	tup = heap_form_tuple(RelationGetDescr(rel), values, nulls);

	/* Insert tuple into catalog. */
	CatalogTupleInsert(rel, tup);
	heap_freetuple(tup);

	/* Register dependencies as needed */
	ObjectAddressSet(myself, PublicationRelRelationId, pubreloid);

	/* Add dependency on the publication */
	ObjectAddressSet(referenced, PublicationRelationId, pubid);
	recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO);

	/* Add dependency on the relation */
	ObjectAddressSet(referenced, RelationRelationId, relid);
	recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO);

	/* Add dependency on the objects mentioned in the qualifications */
	if (pri->whereClause)
		recordDependencyOnSingleRelExpr(&myself, pri->whereClause, relid,
										DEPENDENCY_NORMAL, DEPENDENCY_NORMAL,
										false);

	/* Add dependency on the columns, if any are listed */
	for (int i = 0; i < natts; i++)
	{
		ObjectAddressSubSet(referenced, RelationRelationId, relid, attarray[i]);
		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
	}

	/* Close the table. */
	table_close(rel, RowExclusiveLock);

	/*
	 * Invalidate relcache so that publication info is rebuilt.
	 *
	 * For the partitioned tables, we must invalidate all partitions contained
	 * in the respective partition hierarchies, not just the one explicitly
	 * mentioned in the publication. This is required because we implicitly
	 * publish the child tables when the parent table is published.
	 */
	relids = GetPubPartitionOptionRelations(relids, PUBLICATION_PART_ALL,
											relid);

	InvalidatePublicationRels(relids);

	return myself;
}

/* qsort comparator for attnums */
static int
compare_int16(const void *a, const void *b)
{
	int			av = *(const int16 *) a;
	int			bv = *(const int16 *) b;

	/* this can't overflow if int is wider than int16 */
	return (av - bv);
}

/*
 * Translate a list of column names to an array of attribute numbers
 * and a Bitmapset with them; verify that each attribute is appropriate
 * to have in a publication column list (no system or generated attributes,
 * no duplicates).  Additional checks with replica identity are done later;
 * see check_publication_columns.
 *
 * Note that the attribute numbers are *not* offset by
 * FirstLowInvalidHeapAttributeNumber; system columns are forbidden so this
 * is okay.
 */
static void
publication_translate_columns(Relation targetrel, List *columns,
							  int *natts, AttrNumber **attrs)
{
	AttrNumber *attarray = NULL;
	Bitmapset  *set = NULL;
	ListCell   *lc;
	int			n = 0;
	TupleDesc	tupdesc = RelationGetDescr(targetrel);

	/* Bail out when no column list defined. */
	if (!columns)
		return;

	/*
	 * Translate list of columns to attnums. We prohibit system attributes and
	 * make sure there are no duplicate columns.
	 */
	attarray = palloc(sizeof(AttrNumber) * list_length(columns));
	foreach(lc, columns)
	{
		char	   *colname = strVal(lfirst(lc));
		AttrNumber	attnum = get_attnum(RelationGetRelid(targetrel), colname);

		if (attnum == InvalidAttrNumber)
			ereport(ERROR,
					errcode(ERRCODE_UNDEFINED_COLUMN),
					errmsg("column \"%s\" of relation \"%s\" does not exist",
						   colname, RelationGetRelationName(targetrel)));

		if (!AttrNumberIsForUserDefinedAttr(attnum))
			ereport(ERROR,
					errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
					errmsg("cannot use system column \"%s\" in publication column list",
						   colname));

		if (TupleDescAttr(tupdesc, attnum - 1)->attgenerated)
			ereport(ERROR,
					errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
					errmsg("cannot use generated column \"%s\" in publication column list",
						   colname));

		if (bms_is_member(attnum, set))
			ereport(ERROR,
					errcode(ERRCODE_DUPLICATE_OBJECT),
					errmsg("duplicate column \"%s\" in publication column list",
						   colname));

		set = bms_add_member(set, attnum);
		attarray[n++] = attnum;
	}

	/* Be tidy, so that the catalog representation is always sorted */
	qsort(attarray, n, sizeof(AttrNumber), compare_int16);

	*natts = n;
	*attrs = attarray;

	bms_free(set);
}

/*
 * Transform a column list (represented by an array Datum) to a bitmapset.
 *
 * If columns isn't NULL, add the column numbers to that set.
 *
 * If mcxt isn't NULL, build the bitmapset in that context.
 */
Bitmapset *
pub_collist_to_bitmapset(Bitmapset *columns, Datum pubcols, MemoryContext mcxt)
{
	Bitmapset  *result = NULL;
	ArrayType  *arr;
	int			nelems;
	int16	   *elems;
	MemoryContext oldcxt = NULL;

	/*
	 * If an existing bitmap was provided, use it. Otherwise just use NULL and
	 * build a new bitmap.
	 */
	if (columns)
		result = columns;

	arr = DatumGetArrayTypeP(pubcols);
	nelems = ARR_DIMS(arr)[0];
	elems = (int16 *) ARR_DATA_PTR(arr);

	/* If a memory context was specified, switch to it. */
	if (mcxt)
		oldcxt = MemoryContextSwitchTo(mcxt);

	for (int i = 0; i < nelems; i++)
		result = bms_add_member(result, elems[i]);

	if (mcxt)
		MemoryContextSwitchTo(oldcxt);

	return result;
}

/*
 * Insert new publication / schema mapping.
 */
ObjectAddress
publication_add_schema(Oid pubid, Oid schemaid, bool if_not_exists)
{
	Relation	rel;
	HeapTuple	tup;
	Datum		values[Natts_pg_publication_namespace];
	bool		nulls[Natts_pg_publication_namespace];
	Oid			psschid;
	Publication *pub = GetPublication(pubid);
	List	   *schemaRels = NIL;
	ObjectAddress myself,
				referenced;

	rel = table_open(PublicationNamespaceRelationId, RowExclusiveLock);

	/*
	 * Check for duplicates. Note that this does not really prevent
	 * duplicates, it's here just to provide nicer error message in common
	 * case. The real protection is the unique key on the catalog.
	 */
	if (SearchSysCacheExists2(PUBLICATIONNAMESPACEMAP,
							  ObjectIdGetDatum(schemaid),
							  ObjectIdGetDatum(pubid)))
	{
		table_close(rel, RowExclusiveLock);

		if (if_not_exists)
			return InvalidObjectAddress;

		ereport(ERROR,
				(errcode(ERRCODE_DUPLICATE_OBJECT),
				 errmsg("schema \"%s\" is already member of publication \"%s\"",
						get_namespace_name(schemaid), pub->name)));
	}

	check_publication_add_schema(schemaid);

	/* Form a tuple */
	memset(values, 0, sizeof(values));
	memset(nulls, false, sizeof(nulls));

	psschid = GetNewOidWithIndex(rel, PublicationNamespaceObjectIndexId,
								 Anum_pg_publication_namespace_oid);
	values[Anum_pg_publication_namespace_oid - 1] = ObjectIdGetDatum(psschid);
	values[Anum_pg_publication_namespace_pnpubid - 1] =
		ObjectIdGetDatum(pubid);
	values[Anum_pg_publication_namespace_pnnspid - 1] =
		ObjectIdGetDatum(schemaid);

	tup = heap_form_tuple(RelationGetDescr(rel), values, nulls);

	/* Insert tuple into catalog */
	CatalogTupleInsert(rel, tup);
	heap_freetuple(tup);

	ObjectAddressSet(myself, PublicationNamespaceRelationId, psschid);

	/* Add dependency on the publication */
	ObjectAddressSet(referenced, PublicationRelationId, pubid);
	recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO);

	/* Add dependency on the schema */
	ObjectAddressSet(referenced, NamespaceRelationId, schemaid);
	recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO);

	/* Close the table */
	table_close(rel, RowExclusiveLock);

	/*
	 * Invalidate relcache so that publication info is rebuilt. See
	 * publication_add_relation for why we need to consider all the
	 * partitions.
	 */
	schemaRels = GetSchemaPublicationRelations(schemaid,
											   PUBLICATION_PART_ALL);
	InvalidatePublicationRels(schemaRels);

	return myself;
}

/* Gets list of publication oids for a relation */
List *
GetRelationPublications(Oid relid)
{
	List	   *result = NIL;
	CatCList   *pubrellist;
	int			i;

	/* Find all publications associated with the relation. */
	pubrellist = SearchSysCacheList1(PUBLICATIONRELMAP,
									 ObjectIdGetDatum(relid));
	for (i = 0; i < pubrellist->n_members; i++)
	{
		HeapTuple	tup = &pubrellist->members[i]->tuple;
		Oid			pubid = ((Form_pg_publication_rel) GETSTRUCT(tup))->prpubid;

		result = lappend_oid(result, pubid);
	}

	ReleaseSysCacheList(pubrellist);

	return result;
}

/*
 * Gets list of relation oids for a publication.
 *
 * This should only be used FOR TABLE publications, the FOR ALL TABLES
 * should use GetAllTablesPublicationRelations().
 */
List *
GetPublicationRelations(Oid pubid, PublicationPartOpt pub_partopt)
{
	List	   *result;
	Relation	pubrelsrel;
	ScanKeyData scankey;
	SysScanDesc scan;
	HeapTuple	tup;

	/* Find all publications associated with the relation. */
	pubrelsrel = table_open(PublicationRelRelationId, AccessShareLock);

	ScanKeyInit(&scankey,
				Anum_pg_publication_rel_prpubid,
				BTEqualStrategyNumber, F_OIDEQ,
				ObjectIdGetDatum(pubid));

	scan = systable_beginscan(pubrelsrel, PublicationRelPrpubidIndexId,
							  true, NULL, 1, &scankey);

	result = NIL;
	while (HeapTupleIsValid(tup = systable_getnext(scan)))
	{
		Form_pg_publication_rel pubrel;

		pubrel = (Form_pg_publication_rel) GETSTRUCT(tup);
		result = GetPubPartitionOptionRelations(result, pub_partopt,
												pubrel->prrelid);
	}

	systable_endscan(scan);
	table_close(pubrelsrel, AccessShareLock);

	/* Now sort and de-duplicate the result list */
	list_sort(result, list_oid_cmp);
	list_deduplicate_oid(result);

	return result;
}

/*
 * Gets list of publication oids for publications marked as FOR ALL TABLES.
 */
List *
GetAllTablesPublications(void)
{
	List	   *result;
	Relation	rel;
	ScanKeyData scankey;
	SysScanDesc scan;
	HeapTuple	tup;

	/* Find all publications that are marked as for all tables. */
	rel = table_open(PublicationRelationId, AccessShareLock);

	ScanKeyInit(&scankey,
				Anum_pg_publication_puballtables,
				BTEqualStrategyNumber, F_BOOLEQ,
				BoolGetDatum(true));

	scan = systable_beginscan(rel, InvalidOid, false,
							  NULL, 1, &scankey);

	result = NIL;
	while (HeapTupleIsValid(tup = systable_getnext(scan)))
	{
		Oid			oid = ((Form_pg_publication) GETSTRUCT(tup))->oid;

		result = lappend_oid(result, oid);
	}

	systable_endscan(scan);
	table_close(rel, AccessShareLock);

	return result;
}

/*
 * Gets list of all relation published by FOR ALL TABLES publication(s).
 *
 * If the publication publishes partition changes via their respective root
 * partitioned tables, we must exclude partitions in favor of including the
 * root partitioned tables.
 */
List *
GetAllTablesPublicationRelations(bool pubviaroot)
{
	Relation	classRel;
	ScanKeyData key[1];
	TableScanDesc scan;
	HeapTuple	tuple;
	List	   *result = NIL;

	classRel = table_open(RelationRelationId, AccessShareLock);

	ScanKeyInit(&key[0],
				Anum_pg_class_relkind,
				BTEqualStrategyNumber, F_CHAREQ,
				CharGetDatum(RELKIND_RELATION));

	scan = table_beginscan_catalog(classRel, 1, key);

	while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
	{
		Form_pg_class relForm = (Form_pg_class) GETSTRUCT(tuple);
		Oid			relid = relForm->oid;

		if (is_publishable_class(relid, relForm) &&
			!(relForm->relispartition && pubviaroot))
			result = lappend_oid(result, relid);
	}

	table_endscan(scan);

	if (pubviaroot)
	{
		ScanKeyInit(&key[0],
					Anum_pg_class_relkind,
					BTEqualStrategyNumber, F_CHAREQ,
					CharGetDatum(RELKIND_PARTITIONED_TABLE));

		scan = table_beginscan_catalog(classRel, 1, key);

		while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
		{
			Form_pg_class relForm = (Form_pg_class) GETSTRUCT(tuple);
			Oid			relid = relForm->oid;

			if (is_publishable_class(relid, relForm) &&
				!relForm->relispartition)
				result = lappend_oid(result, relid);
		}

		table_endscan(scan);
	}

	table_close(classRel, AccessShareLock);
	return result;
}

/*
 * Gets the list of schema oids for a publication.
 *
 * This should only be used FOR TABLES IN SCHEMA publications.
 */
List *
GetPublicationSchemas(Oid pubid)
{
	List	   *result = NIL;
	Relation	pubschsrel;
	ScanKeyData scankey;
	SysScanDesc scan;
	HeapTuple	tup;

	/* Find all schemas associated with the publication */
	pubschsrel = table_open(PublicationNamespaceRelationId, AccessShareLock);

	ScanKeyInit(&scankey,
				Anum_pg_publication_namespace_pnpubid,
				BTEqualStrategyNumber, F_OIDEQ,
				ObjectIdGetDatum(pubid));

	scan = systable_beginscan(pubschsrel,
							  PublicationNamespacePnnspidPnpubidIndexId,
							  true, NULL, 1, &scankey);
	while (HeapTupleIsValid(tup = systable_getnext(scan)))
	{
		Form_pg_publication_namespace pubsch;

		pubsch = (Form_pg_publication_namespace) GETSTRUCT(tup);

		result = lappend_oid(result, pubsch->pnnspid);
	}

	systable_endscan(scan);
	table_close(pubschsrel, AccessShareLock);

	return result;
}

/*
 * Gets the list of publication oids associated with a specified schema.
 */
List *
GetSchemaPublications(Oid schemaid)
{
	List	   *result = NIL;
	CatCList   *pubschlist;
	int			i;

	/* Find all publications associated with the schema */
	pubschlist = SearchSysCacheList1(PUBLICATIONNAMESPACEMAP,
									 ObjectIdGetDatum(schemaid));
	for (i = 0; i < pubschlist->n_members; i++)
	{
		HeapTuple	tup = &pubschlist->members[i]->tuple;
		Oid			pubid = ((Form_pg_publication_namespace) GETSTRUCT(tup))->pnpubid;

		result = lappend_oid(result, pubid);
	}

	ReleaseSysCacheList(pubschlist);

	return result;
}

/*
 * Get the list of publishable relation oids for a specified schema.
 */
List *
GetSchemaPublicationRelations(Oid schemaid, PublicationPartOpt pub_partopt)
{
	Relation	classRel;
	ScanKeyData key[1];
	TableScanDesc scan;
	HeapTuple	tuple;
	List	   *result = NIL;

	Assert(OidIsValid(schemaid));

	classRel = table_open(RelationRelationId, AccessShareLock);

	ScanKeyInit(&key[0],
				Anum_pg_class_relnamespace,
				BTEqualStrategyNumber, F_OIDEQ,
				schemaid);

	/* get all the relations present in the specified schema */
	scan = table_beginscan_catalog(classRel, 1, key);
	while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
	{
		Form_pg_class relForm = (Form_pg_class) GETSTRUCT(tuple);
		Oid			relid = relForm->oid;
		char		relkind;

		if (!is_publishable_class(relid, relForm))
			continue;

		relkind = get_rel_relkind(relid);
		if (relkind == RELKIND_RELATION)
			result = lappend_oid(result, relid);
		else if (relkind == RELKIND_PARTITIONED_TABLE)
		{
			List	   *partitionrels = NIL;

			/*
			 * It is quite possible that some of the partitions are in a
			 * different schema than the parent table, so we need to get such
			 * partitions separately.
			 */
			partitionrels = GetPubPartitionOptionRelations(partitionrels,
														   pub_partopt,
														   relForm->oid);
			result = list_concat_unique_oid(result, partitionrels);
		}
	}

	table_endscan(scan);
	table_close(classRel, AccessShareLock);
	return result;
}

/*
 * Gets the list of all relations published by FOR TABLES IN SCHEMA
 * publication.
 */
List *
GetAllSchemaPublicationRelations(Oid pubid, PublicationPartOpt pub_partopt)
{
	List	   *result = NIL;
	List	   *pubschemalist = GetPublicationSchemas(pubid);
	ListCell   *cell;

	foreach(cell, pubschemalist)
	{
		Oid			schemaid = lfirst_oid(cell);
		List	   *schemaRels = NIL;

		schemaRels = GetSchemaPublicationRelations(schemaid, pub_partopt);
		result = list_concat(result, schemaRels);
	}

	return result;
}

/*
 * Get publication using oid
 *
 * The Publication struct and its data are palloc'ed here.
 */
Publication *
GetPublication(Oid pubid)
{
	HeapTuple	tup;
	Publication *pub;
	Form_pg_publication pubform;

	tup = SearchSysCache1(PUBLICATIONOID, ObjectIdGetDatum(pubid));
	if (!HeapTupleIsValid(tup))
		elog(ERROR, "cache lookup failed for publication %u", pubid);

	pubform = (Form_pg_publication) GETSTRUCT(tup);

	pub = (Publication *) palloc(sizeof(Publication));
	pub->oid = pubid;
	pub->name = pstrdup(NameStr(pubform->pubname));
	pub->alltables = pubform->puballtables;
	pub->pubactions.pubinsert = pubform->pubinsert;
	pub->pubactions.pubupdate = pubform->pubupdate;
	pub->pubactions.pubdelete = pubform->pubdelete;
	pub->pubactions.pubtruncate = pubform->pubtruncate;
	pub->pubviaroot = pubform->pubviaroot;

	ReleaseSysCache(tup);

	return pub;
}


/*
 * Get Publication using name.
 */
Publication *
GetPublicationByName(const char *pubname, bool missing_ok)
{
	Oid			oid;

	oid = get_publication_oid(pubname, missing_ok);

	return OidIsValid(oid) ? GetPublication(oid) : NULL;
}

/*
 * get_publication_oid - given a publication name, look up the OID
 *
 * If missing_ok is false, throw an error if name not found.  If true, just
 * return InvalidOid.
 */
Oid
get_publication_oid(const char *pubname, bool missing_ok)
{
	Oid			oid;

	oid = GetSysCacheOid1(PUBLICATIONNAME, Anum_pg_publication_oid,
						  CStringGetDatum(pubname));
	if (!OidIsValid(oid) && !missing_ok)
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("publication \"%s\" does not exist", pubname)));
	return oid;
}

/*
 * get_publication_name - given a publication Oid, look up the name
 *
 * If missing_ok is false, throw an error if name not found.  If true, just
 * return NULL.
 */
char *
get_publication_name(Oid pubid, bool missing_ok)
{
	HeapTuple	tup;
	char	   *pubname;
	Form_pg_publication pubform;

	tup = SearchSysCache1(PUBLICATIONOID, ObjectIdGetDatum(pubid));

	if (!HeapTupleIsValid(tup))
	{
		if (!missing_ok)
			elog(ERROR, "cache lookup failed for publication %u", pubid);
		return NULL;
	}

	pubform = (Form_pg_publication) GETSTRUCT(tup);
	pubname = pstrdup(NameStr(pubform->pubname));

	ReleaseSysCache(tup);

	return pubname;
}

/*
 * Returns information of tables in a publication.
 */
Datum
pg_get_publication_tables(PG_FUNCTION_ARGS)
{
#define NUM_PUBLICATION_TABLES_ELEM	3
	FuncCallContext *funcctx;
	char	   *pubname = text_to_cstring(PG_GETARG_TEXT_PP(0));
	Publication *publication;
	List	   *tables;

	/* stuff done only on the first call of the function */
	if (SRF_IS_FIRSTCALL())
	{
		TupleDesc	tupdesc;
		MemoryContext oldcontext;

		/* create a function context for cross-call persistence */
		funcctx = SRF_FIRSTCALL_INIT();

		/* switch to memory context appropriate for multiple function calls */
		oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);

		publication = GetPublicationByName(pubname, false);

		/*
		 * Publications support partitioned tables, although all changes are
		 * replicated using leaf partition identity and schema, so we only
		 * need those.
		 */
		if (publication->alltables)
		{
			tables = GetAllTablesPublicationRelations(publication->pubviaroot);
		}
		else
		{
			List	   *relids,
					   *schemarelids;

			relids = GetPublicationRelations(publication->oid,
											 publication->pubviaroot ?
											 PUBLICATION_PART_ROOT :
											 PUBLICATION_PART_LEAF);
			schemarelids = GetAllSchemaPublicationRelations(publication->oid,
															publication->pubviaroot ?
															PUBLICATION_PART_ROOT :
															PUBLICATION_PART_LEAF);
			tables = list_concat_unique_oid(relids, schemarelids);

			/*
			 * If the publication publishes partition changes via their
			 * respective root partitioned tables, we must exclude partitions
			 * in favor of including the root partitioned tables. Otherwise,
			 * the function could return both the child and parent tables
			 * which could cause data of the child table to be
			 * double-published on the subscriber side.
			 */
			if (publication->pubviaroot)
				tables = filter_partitions(tables);
		}

		/* Construct a tuple descriptor for the result rows. */
		tupdesc = CreateTemplateTupleDesc(NUM_PUBLICATION_TABLES_ELEM);
		TupleDescInitEntry(tupdesc, (AttrNumber) 1, "relid",
						   OIDOID, -1, 0);
		TupleDescInitEntry(tupdesc, (AttrNumber) 2, "attrs",
						   INT2VECTOROID, -1, 0);
		TupleDescInitEntry(tupdesc, (AttrNumber) 3, "qual",
						   PG_NODE_TREEOID, -1, 0);

		funcctx->tuple_desc = BlessTupleDesc(tupdesc);
		funcctx->user_fctx = (void *) tables;

		MemoryContextSwitchTo(oldcontext);
	}

	/* stuff done on every call of the function */
	funcctx = SRF_PERCALL_SETUP();
	tables = (List *) funcctx->user_fctx;

	if (funcctx->call_cntr < list_length(tables))
	{
		HeapTuple	pubtuple = NULL;
		HeapTuple	rettuple;
		Oid			relid = list_nth_oid(tables, funcctx->call_cntr);
		Oid			schemaid = get_rel_namespace(relid);
		Datum		values[NUM_PUBLICATION_TABLES_ELEM];
		bool		nulls[NUM_PUBLICATION_TABLES_ELEM];

		/*
		 * Form tuple with appropriate data.
		 */
		MemSet(nulls, 0, sizeof(nulls));
		MemSet(values, 0, sizeof(values));

		publication = GetPublicationByName(pubname, false);

		values[0] = ObjectIdGetDatum(relid);

		/*
		 * We don't consider row filters or column lists for FOR ALL TABLES or
		 * FOR TABLES IN SCHEMA publications.
		 */
		if (!publication->alltables &&
			!SearchSysCacheExists2(PUBLICATIONNAMESPACEMAP,
								   ObjectIdGetDatum(schemaid),
								   ObjectIdGetDatum(publication->oid)))
			pubtuple = SearchSysCacheCopy2(PUBLICATIONRELMAP,
										   ObjectIdGetDatum(relid),
										   ObjectIdGetDatum(publication->oid));

		if (HeapTupleIsValid(pubtuple))
		{
			/* Lookup the column list attribute. */
			values[1] = SysCacheGetAttr(PUBLICATIONRELMAP, pubtuple,
										Anum_pg_publication_rel_prattrs,
										&(nulls[1]));

			/* Null indicates no filter. */
			values[2] = SysCacheGetAttr(PUBLICATIONRELMAP, pubtuple,
										Anum_pg_publication_rel_prqual,
										&(nulls[2]));
		}
		else
		{
			nulls[1] = true;
			nulls[2] = true;
		}

		rettuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);

		SRF_RETURN_NEXT(funcctx, HeapTupleGetDatum(rettuple));
	}

	SRF_RETURN_DONE(funcctx);
}